The role of microbes in tea cultivation
Description
The adoption of biological techniques for sustainable tea cultivation is a pertinent strategy for an efficient and ideal agricultural growth with minimal generation of adverse environmental impacts that may affect water resources, ecosystems or the quality of human life. Modern agriculture offers immense opportunity to exploit beneficial soil microbial resources such as nitrogen fixers, phosphate solubilizers, potash mobilizers, cellulose degraders, AM fungi, etc., as well as biopesticides (microbial biocontrol agents and entomopathogens), to optimize crop benefit and maintain soil quality. According to Raja (2013) there is a rising trend towards organic agriculture using biological-based organics as an alternative to agrochemicals. Organic farming ensures food safety as well as aiding biodiversity conservation and functioning in the soil. It is highly likely to be dependent on the native soil microflora which constitutes all kinds of useful bacteria and fungi including the AMF and PGPR. A synergistic interaction of PGPR and AMF is recorded as highly suitable to fertilizer use patterns in agricultural soil. An enhanced plant nutrient-use efficiency with PGPR and AMF in an integrated nutrient management system has been achieved by Adesemoye et al. (2008), and thereby suggested the application of microbes with reduced doses of fertilizer in agricultural soil. Microbial inoculants are of paramount significance in integrated nutrient and pest management schedules and thereby assist in the generation of healthy agricultural practices (Adesemoye and Kloepper, 2009). Microbial biofertilizers and biopesticides fulfil diverse beneficial interactions in tea soil and thereby lead to promising solutions for sustainability. As the rhizosphere is an ideal habitat for the isolation of beneficial microorganisms (Mendes et al., 2013), considerable effort has been made to explore the microbial diversity of the surface and sub-surface soil of tea plants under cultivation in diverse topographical regions. Different species of microbial inoculants are now known to antagonize tea pathogens via mycoparasitism, producing volatile and non-volatile antibiotics, competing for nutrients and space, as well as their diverse beneficial activities contributing towards enhanced crop production. The use of microbials such as viruses (NPV/GV), spore-forming bacteria (Bacillus strains) and fungi (Beauveria, Metarhizium, Verticillium, Paecilomyces), holds great promise in this regard. Most of the tea estates, however, refrain from risking crop loss due to pest attack and liberally use synthetic pesticides under ‘no threshold category of pest management’ (Pedigo, 2002), and as microbial insecticides are pest specific, the potential market for these products is rather limited.